ASTM B435 UNS N06230 (Haynes 230) – Nickel-Chromium-Tungsten-Molybdenum Alloy for High-Temperature Service
UNS N06230 (Haynes 230) is a nickel-chromium-tungsten-molybdenum alloy specifically engineered for exceptional high-temperature strength, outstanding oxidation resistance, and excellent long-term thermal stability. It combines solid-solution strengthening with a unique lanthanum addition that enhances oxide scale adhesion. This alloy is widely used in gas turbine combustion hardware, transition ducts, and thermocouple sheaths where reliability at temperatures up to 1093°C (2000°F) is critical.
1. Product Specifications & Physical Data
ASTM B435 covers UNS N06230 in the form of rolled plate, sheet, and strip for heat-resisting and general corrosive service. The alloy is also available in billet, bar, wire, forging stock, pipe, and tubing, typically supplied in the solution-annealed condition.
Available Forms: Plate, sheet, strip, foil, billet, bar, wire, forging stock, welding products, pipe, and tubing .
Specifications: ASTM B435 (plate/sheet/strip), AMS 5878 (sheet/strip), AMS 5891 (bar/forgings), UNS N06230 .
| Chemical Composition (Weight %) | UNS N06230 Specification |
|---|---|
| Nickel (Ni) | Balance |
| Chromium (Cr) | 20.0 - 24.0 |
| Tungsten (W) | 13.0 - 15.0 |
| Molybdenum (Mo) | 1.0 - 3.0 |
| Cobalt (Co) | 5.0 max. |
| Iron (Fe) | 3.0 max. |
| Manganese (Mn) | 0.30 - 1.0 |
| Silicon (Si) | 0.25 - 0.75 |
| Carbon (C) | 0.05 - 0.15 |
| Aluminum (Al) | 0.20 - 0.50 |
| Lanthanum (La) | 0.005 - 0.05 |
| Physical Properties | Metric | Imperial |
|---|---|---|
| Density | 8.97 g/cm³ | 0.324 lb/in³ |
| Melting Range | 1301 - 1377°C | 2374 - 2511°F |
| Modulus of Elasticity (RT) | 211 GPa | 30.6 × 10⁶ psi |
| Thermal Conductivity (RT) | 8.9 W/m·K | 62 BTU·in/hr·ft²·°F |
| Coefficient of Expansion (20-1000°C) | 14.2 µm/m·°C | 7.9 µin/in·°F |
| Mechanical Properties (Solution Annealed Plate) | Metric | Imperial |
|---|---|---|
| Tensile Strength (RT) | 860 MPa | 125 ksi |
| Yield Strength (0.2% offset, RT) | 395 MPa | 57 ksi |
| Elongation (RT) | 50% | 50% |
| Tensile Strength (760°C / 1400°F) | 605 MPa | 88 ksi |
| Tensile Strength (980°C / 1800°F) | 240 MPa | 35 ksi |
| Hardness (Annealed) | 94 HRB | 94 HRB |
2. Operating Conditions & Selection Criteria
UNS N06230 is specified when designers require exceptional high-temperature strength, oxidation resistance, and thermal stability for components operating in the most demanding environments.
Service Temperature Range: Optimized for continuous operation up to 1093°C (2000°F); retains useful strength through this range .
Strengthening Mechanism: Solid-solution strengthened by tungsten and molybdenum in a nickel-chromium matrix; lanthanum addition enhances oxide scale adhesion .
Oxidation Resistance: Outstanding resistance to oxidizing and nitriding environments; superior to many nickel-base alloys at elevated temperatures .
Thermal Stability: Excellent long-term stability; resists embrittlement and phase transformation during prolonged exposure .
Corrosion Resistance: Good resistance to carburization and sulfidation; suitable for combustion environments .
Fabricability: Excellent forming and welding characteristics; easily fabricated into complex components .
3. Fabrication & Material Comparison
Solution Annealing: 1177-1246°C (2150-2275°F), rapid cool (water quench or accelerated air cool). Supplied in this condition for optimal properties .
Hot Working: 1177-1232°C (2150-2250°F); reheat as necessary; avoid working below 927°C .
Cold Working: Good formability in annealed condition; intermediate annealing may be required for severe deformation .
Machining: Similar to other nickel-base alloys; requires rigid setups, sharp tools, and adequate coolant .
Welding: Excellent weldability using GTAW, GMAW, and resistance welding; matching filler metal recommended .
Material Comparison:
vs. Hastelloy X: Higher creep strength and oxidation resistance; better thermal stability .
vs. Inconel 625: Superior high-temperature strength above 800°C; better oxidation resistance .
vs. Haynes 188: Comparable high-temperature performance; nickel vs. cobalt base; different oxidation characteristics .
vs. 310 Stainless: Significantly higher creep strength; better oxidation resistance at elevated temperatures .
| Property Comparison | UNS N06230 | Hastelloy X | Inconel 625 |
|---|---|---|---|
| Maximum Service Temp | 1093°C (2000°F) | 1093°C (2000°F) | 982°C (1800°F) |
| Creep Strength (980°C) | Excellent | Good | Moderate |
| Oxidation Resistance | Outstanding | Good | Good |
| Fabricability | Excellent | Excellent | Good |
Applications
Gas Turbine Engines: Combustion cans, transition ducts, flame holders, burner components
Power Generation: Industrial gas turbine hardware, combustion liners
Aerospace: Afterburner components, exhaust nozzles, engine casings
Industrial Processing: Heat treating fixtures, furnace components, thermocouple sheaths
Chemical Processing: High-temperature reactor components, catalyst grid supports
Contact ZYTC Alloy for certified UNS N06230 materials with complete traceability, ASTM B435 specifications, technical datasheets, and competitive pricing on standard sizes or custom-fabricated components.
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